Nim cell magic for Jupyter and JLab Notebooks

nim_magic.py

"""
nim_magic.py
Jupyter cell magic for your favorite programming language.

Requirements: Nim (https://nim-lang.org), nimpy (`nimble install nimpy`, thanks to @yglukhov for this great library!)

Just put this file in some Python import dir

and then, in a Jupyter or JLab Notebook:

In [1]:
    %load_ext nim_magic


In [2]:
    %%nim mytest -d:release
    proc greet(name: string): string {.exportpy.} =
        return "Hello, " & name & "!"


In [3]:
    mytest.greet("World")
"""


from IPython.core.magic import Magics, magics_class, cell_magic, needs_local_scope
from importlib import __import__


@magics_class
class NimMagics(Magics):

    @cell_magic
    def nim(self, options, code):
        """options must include the module name.
        In addtion, further compile options, e.g. "-d:release" can be put here (separated by space)."""
        import subprocess as sp
        glbls = self.shell.user_ns
        opt_list = options.split(" ", 1)
        name = opt_list[0]
        if name == "":
            raise ValueError("module name is required. Try %%nim <mymodule> <compiler options>.")
        if len(opt_list) > 1:
            opt_str = opt_list[1]
        else:
            opt_str = ""
        code = "import nimpy\n\n" + code
        open("{}.nim".format(name), "w").write(code)
        cmd = "nim c {} --app:lib --out:{}.so {}.nim".format(opt_str, name, name)
        cp = sp.run(cmd, shell=True, check=False, encoding="utf8", stdout=sp.PIPE, stderr=sp.PIPE)
        print(cp.stderr)
        if cp.returncode == 0:
            import_exec = "import {}".format(name)
            exec(import_exec, glbls)


def load_ipython_extension(ipython):
    """
    Any module file that define a function named `load_ipython_extension`
    can be loaded via `%load_ext module.path` or be configured to be
    autoloaded by IPython at startup time.
    """
    # You can register the class itself without instantiating it.  IPython will
    # call the default constructor on it.
    ipython.register_magics(NimMagics)